Extrusion apparatus and method for orienting plastic material by using an extrusion apparatus

Abstract

An extrusion apparatus including at least one conical stator, and at least one conical rotor. The rotor is adapted for defibering or orienting a plastic material. The apparatus has an opening for receiving an elongate product or mandrel. The product or mandrel may be disposed in the apparatus such that, with the product or mandrel received in the opening, an extrusion conduit is defined in the opening between the product or mandrel and the rotor and stator. The rotor and stator are disposed with respect to one another to form a supply opening wherein the plastic material flows between the stator and rotor and is pressed into the extrusion conduit. A method for extrusion is also described involving the apparatus;

What is claimed is:  
     
       1. An extrusion apparatus comprising: 
       (a) at least one conical stator;  
       (b) at least one conical rotor, said rotor comprising orienting means for defibering or orienting a plastic material;  
       (c) conduit means defining an opening in the apparatus for receiving an elongate product or mandrel, said conduit means being disposed in the apparatus such that, with the product or mandrel received in the opening, an extrusion conduit is defined in the opening between the product or mandrel and the rotor and stator, said rotor and stator being disposed with respect to one another to form a supply opening wherein the plastic material flows between the stator and rotor and is pressed into the extrusion conduit, said orienting means being disposed at an end of the rotor proximate to the extrusion conduit, said orienting means comprising a substantially cylindrical extension extending to the extrusion conduit and disposed at the end of the rotor.  
     
     
       2. An extrusion apparatus according to claim  1 , wherein said orienting means comprise a plurality of apertures passing through the rotor. 
     
     
       3. An extrusion apparatus according to claim  1 , wherein said orienting means comprise a plurality of apertures passing through the cylindrical extension. 
     
     
       4. An extrusion apparatus according to claim  1  comprising an annular flange at the end of the cylindrical extension. 
     
     
       5. An extrusion apparatus according to claim  4 , wherein the annular flange comprises a plurality of openings passing through it. 
     
     
       6. An extrusion apparatus according to claim  1 , wherein the cylindrical extension enlarges substantially conically in the direction of flow of the plastic material, said apparatus comprising first means for conducting plastic material flowing in the supply opening from a back of the rotor to an outer surface of the cylindrical extension for mixing with plastic material flowing in the supply opening at a front of the rotor, and second means for conducting plastic material on the outer surface of the cylindrical extension through the cylindrical extension and into an interior of the cylindrical extension. 
     
     
       7. An extrusion apparatus according to claim  6 , wherein the first and second means collectively comprise a stator extension disposed in back of the rotor that obstructs the supply opening and a plurality of apertures passing through the cylindrical extension. 
     
     
       8. An extrusion apparatus according to claim  1 , wherein the apparatus also comprises at least a second rotor and a second stator, said at least one stator and second stator surrounding the at least one rotor, said apparatus further comprising means for rotating the at least one rotor and second rotor in opposite directions. 
     
     
       9. An extrusion apparatus according to claim  8 , further comprising means disposed between the at least one rotor and the second rotor for cooling plastic material pressed into the extrusion conduit whereby to fix the orientation of the plastic material. 
     
     
       10. An extrusion apparatus according to claim  1 , comprising the elongate product received in the opening and cooling means at an inlet end of the extrusion conduit for an initial cooling of plastic material pressed into the conduit. 
     
     
       11. An extrusion apparatus according to claim  1 , comprising the mandrel received in the opening, said mandrel being heated or cooled. 
     
     
       12. An extrusion apparatus according to claim  11 , wherein the mandrel is an axially movable rod that extends through the extrusion apparatus and that comprises at its end a mandrel cone, said mandrel being heated or cooled. 
     
     
       13. An extrusion apparatus according to claim  12 , wherein the rod comprises at least one seal that is expandable against an inner surface of either the extrusion apparatus or plastic material to be extruded. 
     
     
       14. An extrusion apparatus according to claim  13 , wherein the rod is hollow and the apparatus further comprises a second seal, means for warming or cooling the rod or both, means for expanding the at least one seal, and means for forming a tempering zone between the at least one seal and the second seal. 
     
     
       15. An extrusion apparatus according to claim  1  comprising, at an outlet end of the extrusion conduit, thermal insulation and a cooling nozzle. 
     
     
       16. A method for orienting plastic material during the formation or coating of a cylindrical plastic product comprising: 
       (a) providing an extrusion apparatus comprising at least one conical stator, at least one conical rotor comprising means for defibering or orienting the plastic material, an extrusion conduit and a supply opening between the stator and the rotor from which the plastic material is pressed into the extrusion conduit;  
       (b) introducing the plastic material into the supply opening and rotating the at least one rotor sufficiently rapidly to impart to molecules of the plastic material a helical orientation having a direction that is almost the same as a circumference of the cylindrical plastic product; and  
       (c) drawing the oriented plastic material from the extrusion apparatus in a way that reduces the orientation of the plastic molecules in the circumferential direction whereby the cylindrical plastic product or a coating thereon has an orientation angle that is smaller than that of the oriented plastic material.  
     
     
       17. A method according to claim  16 , wherein the drawing in step (c) comprises drawing the oriented plastic material over a tempered mandrel to stretch the plastic molecules simultaneously in the circumferential direction and in an axial direction. 
     
     
       18. A method according to claim  16 , wherein the plastic material comprises fibers, said method comprising coating the cylindrical plastic product by passing said product through the extrusion apparatus and spinning and crystalizing the fibers of the plastic material thereon with cooling of the product. 
     
     
       19. A method according to claim  16 , wherein the plastic material is a mixture of crosslinked material and the method comprises heating the mixture to a crosslinking temperature with a hot mandrel. 
     
     
       20. A method according to claim  17 , comprising adjusting the length of the tempered mandrel. 
     
     
       21. A method according to claim  16 , comprising tempering the oriented plastic material by decreasing a temperature thereof in a tempering zone. 
     
     
       22. A method according to claim  21 , wherein the temperature is decreased by increasing a length of the tempering zone.